Acromegaly is a rare hormonal disorder in which the body produces too much growth hormone, causing bones, cartilage, and soft tissues to keep growing long after normal development has stopped. It affects roughly 3 to 5 people per million each year, and recent estimates put the total number of people living with it at about 85 to 120 per million. Because changes happen gradually over years, the condition often goes undiagnosed for a decade or more before someone gets an answer.
What Causes Acromegaly
In about 95% of cases, acromegaly is caused by a benign (noncancerous) tumor called an adenoma that grows on the pituitary gland, a pea-sized structure at the base of the brain. This tumor pumps out excessive amounts of growth hormone, which then travels to the liver and triggers overproduction of a second hormone called insulin-like growth factor 1 (IGF-1). IGF-1 is the main driver behind the tissue overgrowth that defines acromegaly. Its receptor exists on cells throughout the body, which is why the effects are so widespread.
In rare cases, a tumor elsewhere in the body produces a signaling hormone that tells the pituitary to release more growth hormone than it should. But pituitary adenomas account for the overwhelming majority of cases.
Acromegaly vs. Gigantism
Growth hormone excess can look very different depending on when it starts. In children and adolescents whose growth plates haven’t yet fused, excess growth hormone causes gigantism, marked by unusually tall stature because the long bones can still lengthen. Once the growth plates close (typically by the late teens), the long bones can no longer grow longer. Excess growth hormone after that point causes acromegaly instead, where bones widen and thicken rather than lengthen, and soft tissues swell.
How Acromegaly Changes the Body
The most recognizable signs involve the face and extremities. Studies report that acral enlargement (widening of the hands and feet) is present in virtually 100% of confirmed cases. People often notice that rings no longer fit or that they’ve gone up several shoe sizes over a few years. Facial features gradually coarsen: the brow ridge becomes more prominent (called frontal bossing), the jaw juts forward, the nose widens, and the tongue may enlarge enough to affect speech or breathing.
Beyond these visible changes, excess growth hormone drives a long list of problems throughout the body:
- Joints and bones: IGF-1 stimulates new bone formation on the surface of existing bones, leading to joint pain, stiffness, and eventually arthritis that can become debilitating.
- Heart and blood pressure: The heart muscle can thicken and enlarge, raising the risk of heart failure. Hypertension is common.
- Blood sugar: Excess growth hormone makes cells resistant to insulin, pushing blood sugar levels up. Many people with acromegaly develop type 2 diabetes or prediabetes.
- Breathing: Thickened tissues in the airway, combined with an enlarged tongue, frequently cause sleep apnea.
- Sweating and skin: Excessive sweating and oily, thickened skin are early and common complaints.
- Headaches and vision: The pituitary tumor itself can press on nearby nerves, causing persistent headaches or narrowing peripheral vision.
Because these changes develop slowly, many people adapt without realizing anything is wrong. It’s common for the diagnosis to come only after a dentist notices jaw changes, a friend sees an old photo and is struck by the difference, or a doctor investigates a related problem like new-onset diabetes or sleep apnea.
How Acromegaly Is Diagnosed
Diagnosis starts with a blood test measuring IGF-1 levels. Because IGF-1 stays relatively stable throughout the day (unlike growth hormone, which fluctuates in pulses), it’s a reliable screening tool. If IGF-1 is elevated or borderline, the next step is a glucose suppression test. You drink a standard glucose solution (75 grams), and your growth hormone is measured over the next two hours. In a healthy person, the sugar load causes growth hormone to drop below 1 ng/mL. If it stays at or above that threshold, the diagnosis is confirmed.
Once blood tests confirm excess growth hormone, an MRI of the pituitary gland is done to locate and measure the tumor. Most adenomas are classified as either microadenomas (under 10 mm) or macroadenomas (10 mm or larger), and the size matters for treatment planning.
Treatment Options
Surgery
The first-line treatment for most people is surgery to remove the pituitary adenoma. Surgeons reach the tumor through the nasal passages and sinuses, avoiding any external incisions. Success depends largely on tumor size. For microadenomas, remission rates reach up to 78%. For macroadenomas, the rate drops to around 53 to 64%, and very large tumors (called giant adenomas) rarely achieve full remission through surgery alone. When surgery doesn’t completely normalize hormone levels, medication becomes the next step.
Medication
Two main classes of drugs are used. The first works by mimicking a natural brain chemical called somatostatin, which tells the pituitary to stop releasing growth hormone. These long-acting injections are given every few weeks and can shrink the tumor while lowering hormone levels. They’re used before surgery in some cases, after surgery when hormone levels remain high, or as the primary treatment when surgery isn’t an option.
The second class takes a different approach entirely. Rather than reducing growth hormone production, it blocks the hormone’s receptor in tissues throughout the body, preventing growth hormone from triggering IGF-1 production in the liver. This treatment, given as a self-administered injection (daily or weekly), normalizes IGF-1 in nearly all patients when dosed correctly, though the required dose varies widely from person to person. Some people do best on a combination of both drug classes.
Radiation
When surgery and medication together don’t achieve full control, targeted radiation therapy can be directed at remaining tumor tissue. Hormone levels typically take months to years to normalize after radiation, so medication is continued in the interim.
Long-Term Outlook
Getting growth hormone and IGF-1 back to normal levels is the central goal, because uncontrolled acromegaly significantly shortens life expectancy. A large Italian study found that people with persistently active disease had a standardized mortality ratio of 2.5, meaning their risk of death was two and a half times that of the general population. Those whose disease was biochemically controlled had a much lower ratio of 1.3, which is still slightly elevated compared to the general population but a major improvement.
Some physical changes, particularly bone and cartilage overgrowth, are permanent even after hormone levels normalize. Joint problems and facial changes won’t reverse. However, soft tissue swelling, excessive sweating, and metabolic problems like insulin resistance do improve, often noticeably, once treatment brings hormones under control. Many people also report better energy, improved mood, and fewer headaches within months of achieving normal hormone levels.